Recognized anatomic variations that lead to patella instability include patella alta and trochlea dysplasia. Lateralization of the extensor mechanism relative to the trochlea is often considered to be a contributing factor; however, controversy remains as to the degree this contributes to instability and how this should be measured. As the tibial tuberosity-trochlear groove (TT-TG) is one of most common imaging measurements to assess lateralization of the extensor mechanism, it is important to understand its strengths and weaknesses. Care needs to be taken while interpreting the TT-TG value as it is affected by many factors. Medializing tibial tubercle osteotomy is sometimes used to correct the TT-TG, but may not truly address the underlying anatomical problem. This review set out to determine whether the TT-TG distance sufficiently summarizes the pathoanatomy, and if this assists with planning of surgery in patellar instability.

Cite this article: Bone Jt Open 2022;3(3):268–274.

Objective: Prospective analysis of early clinical outcome in patients treated with medial patellofemoral ligament reconstruction using an autologous semitendinosus graft plus objective arthroscopic assessment of graft tension and subsequent patella tracking.

Method: 47 consecutive patients underwent 48 procedures between September 2005 and February 2008. All procedures were performed by the senior author using a standardised technique. A semitendinosus autograft is passed extrasynovially between the isometric attachments to the patella and femur and secured with an endobutton and interference screw. The technique includes arthroscopic assessment through a superolateral portal before and after graft placement ensuring correct graft tension and patella tracking before graft fixation. Patients received pre and post operative clinical evaluation, radiological assessment, outcome scoring systems and a satisfaction questionnaire.

Results: 47 patients were followed up with mean age 26 (range 16–49) and minimum follow up of 6 months (mean 13, range 6–35). 26 were male and 22 female. Indications were atraumatic recurrent patella dislocation in 30 patients, traumatic recurrent dislocation in 15 patients, instability in 2 and anterior knee pain in 1 patient. There have been no recurrent dislocations/ subluxations, 2 have had intermittent feelings of instability 6 have complained of medial knee pain and 3 have required further surgery. Kujala Scores improved from 53 (95%CI 28–78) to 78 (95%CI 70–85) and this was statistically significant (p< 0.05). This improvement is mirrored by the other scoring systems used. 94% of patients were satisfied with their operation.

Conclusions: This technique of medial patellofemoral ligament reconstruction is the first described which allows for objective intraoperative evaluation of the required graft tension to optimise patella tracking. The early results of this technique are encouraging.

Introduction: Anterior Knee pain is a very common presentation in Orthopaedic out patient clinics. However, Trochlear Dysplasia as a condition is still not very well understood.

Materials and Methods: Operative findings in patients undergoing Trochleaplasty and in young patients undergoing Patella-femoral arthroplasty were studied. Patients having trochlear dysplasia were identified. All these patients were sent a questionnaire to explore the variety of symptoms they experienced. 87 patients were identified for the study. 71(82%) patients responded to the questionnaire.

Results: Two subgroups were identified, one with dislocation of patella and the other without dislocation of the patella. Patients in patella dislocation group were younger (12 years vs 24) than those who presented without dislocation of patella. Patella dislocation group had more patients with anterior knee pain (71% vs 52%) as teenagers as compared to the group without dislocations. Symptoms such as giving way, lack of trust and unable to participate in sports were more commonly seen in the group with patella dislocation whereas, limited walking distance and difficulty with climbing the stairs were more commonly seen in the group without dislocation. Symptoms such as pain, catching and locking were seen equally amongst the two groups.

Conclusion: We believe that the patients with trochlear dysplasia have a bimodal presentation. Patients with dislocation of patella present earlier than those without patella dislocation. These two groups also have different symptoms at presentation. It is important to identify these subgroups correctly for appropriate management.